Inertial Electrostatic Confinement (IEC) is an approach to nuclear fusion which utilises the properties of electrostatically
accelerated ion-beams instead of hot plasmas. The best known device which uses the principle is the Farnsworth-Hirsch fusor.
It has been argued that such devices have some potential advantages in spaceflight and in-particular as power-supplies for
trans-atmospheric propulsion. This paper builds on previous work in the field and focuses on how the fixing of the fuel for
such reactors in a solid, liquid or encapsulated form may provide a high enough energy-density to make such devices practical
power sources. Several methods of fixing the fuel are discussed; theoretical calculations are presented and applicable
literature is reviewed. Finally, there is a discussion of practical issues and feasibility, together with suggestions for further
work.